January 11, 2010 was a miserable day. The Patriots concluded a 10-6 season — only 2000 (5-11) and 2002 (9-7) were worse under coach Bill Belichick — and they had just been annihilated, 33-14, by the Ravens (at home, mind you) in the first round of the playoffs.

Much of the focus on the outside was on the defense; an 83-yard touchdown run by Ray Rice started the deluge on the first play of the game.

But inside the walls of One Patriot Place, the wheels were in motion to fix the offense. The Patriots didn’t have receiver Wes Welker (knee surgery), and his absence reinforced a larger point: the Patriots were limited in aerial weapons. Brady completed just 54.8 percent of his passes and had an embarrassing 3.7 yards per attempt against the Ravens.

Changes had to be made. In the record-setting 2007 season and in 2008, the Patriots were a receiver-driven offense because they had a lot of them, and they were good. By the end of ’09, things weren’t working out.

“Offensively, we’ve seen this twice now really,” Belichick told his assistant coaches after a Week 5 loss to the Broncos, which was captured in “A Football Life’’ on the NFL Network. “If you just take [Randy] Moss away in the deep part of the field, and get down on Welker, we’re done. We’re done. We can’t run the ball. We can’t throw it to anybody else. We’re done.”

Heading into 2010, things had to change. And who knew what the Patriots were going to be able to get out of Welker after ACL surgery?

Just like he does after every season, Belichick stood in front of his staff on that lousy January day and distributed the postseason tasks: study your group, and find out a way to get better. ASAP.

For quarterbacks coach Bill O’Brien, who was the de facto offensive coordinator, that meant a total retooling.

When it comes to coaching and philosophy, Belichick is not stuck in his ways. He is open to new ideas.

When Belichick and O’Brien were done dissecting the offense, they came to two conclusions:

The team had to get away from the spread-pass, shotgun-run game and get Brady back under center so they can run the ball better and set up the passing game through play-action.

And they had to get two, possibly three tight ends. Benjamin Watson and Chris Baker weren’t good enough.

The Patriots have always had two classes of tight ends. There is the traditional “Y,” whose job requirements read: 6 feet 5 inches or taller, at least 255 pounds, can run but absolutely must be a standout blocker. He has to be a viable receiver, but not a great one.

The “F” or flex tight end is 6-3 or taller, around 235 pounds, must be able to run and be an excellent pass receiver. Does not need to be a good blocker.

Everyone in the building agreed that Aaron Hernandez out of the University of Florida, where he did a little bit of everything, was the prototype “F.”

There was disagreement on the Y. Some were scared off by Rob Gronkowski’s back surgery in college. There also wasn’t agreement on whether Gronkowski as a rookie could think quick enough to play with Brady. But at least one person did have Gronkowski ranked as the No. 1 Y: Belichick.

Through skill and luck, the Patriots landed both in the draft.

It didn’t take the Patriots long to realize they had struck gold with both players. Not only were they the physical prototypes, but both had to be dragged off the practice field because they loved football so much.

Been there, done that

There’s a prevalent notion that Belichick has only recently become enamored with the tight ends (he drafted nine with New England before 2010), and that the Patriots have reinvented the wheel with their system.

Belichick has long ties to tight ends. As an assistant coach with the Lions from 1976-77, Belichick coached Hall of Fame tight end Charlie Sanders and, after the team drafted David Hill in 1976, he put both tight ends on the field at the same time. That was apparently the start of it, but others followed.

Don Coryell (Chargers) and Joe Gibbs (Redskins) used multiple tight ends during the 1980s. And disciples of both, including Chargers coach Norv Turner and Ravens offensive coordinator Cam Cameron, have been using two tight ends for years.

But nobody had found two talents like Gronkowski and Hernandez. And those types are dwindling because of the rise of the spread offense in college.

“When you have two guys that are that capable, it’s real trouble,” said defensive back Ronde Barber, who is in his 16th season with the Buccaneers. “Gronk is more traditional just because of his size.

“But they run a lot of 12 personnel [one back, two tight ends] where they have Hernandez in the game and he can either be end position as a tight end, he can line up in the backfield, or he lines up like a slot receiver. So they give you matchup problems.’’

In the NFL, it’s all about matchups. That’s the power that the multiple tight end set gives the Patriots. Tight ends are, as Falcons coach Mike Smith dubbed them, the “queens on the chessboard.”

Get the right tight ends and you can have a 60-minute advantage.

And we haven’t even touched the no-huddle offense and the personnel advantages the Patriots have since Hernandez can go into the backfield and run the outside zone plays.

Deep thinkers

The scheme is not perfect. Yet.

If the Patriots don’t run the ball enough in situations that they should, then teams with certain personnel — including multiple safeties, like the Giants had in the Super Bowl with Kenny Phillips, Antrel Rolle, and Deon Grant — can clog the middle of the field, where the Patriots’ personnel worked best the past two years.

The Patriots also ran into this problem in the 2010 playoff loss to the Jets, when New York loaded up on defensive backs and the Patriots refused to run against those looks.

Enter receiver Brandon Lloyd.

“The Lloyd signing was so critical,” said NFL Films analyst Greg Cosell. “They needed someone who could at least get down the field. They didn’t have that guy last year.’’

The Patriots have also added two more tight ends, Daniel Fells (Y) and Visanthe Shiancoe (F).

Big advantage

Gronkowski takes two steps back as if to pass block. Then he tries to shove rushing Redskins linebacker Ryan Kerrigan aside. Kerrigan senses something is up and tries to tackle him.

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